Programmed cell death receptor ligand 1 (PD-L1) expression: Epidermal growth factor receptor (EGFR) and Kirsten RAS (KRAS) mutations in second-line therapy (2L) non-small cell lung cancer (NSCLC) patients—A Danish cohort study.

Abstract

e20523 Background: In NSCLC patients who received 2L therapy, we examined the association of PD-L1 expression, mutations in KRAS and EGFR and survival. Methods: 2L NSCLC patients diagnosed during 2001-2012 and with sufficient archival tumour tissue were selected from the Danish Lung Cancer Group Registry. We retrieved patient data from population-based medical registries, and paraffin-embedded tumor tissue from pathology archives. We assessed PD-L1 expression using the Ventana IHC (SP263) validated assay (using 25% cutoff for positivity), and genotyped KRAS and EGFR via PCR-based kits. Follow-up was from the start of 2L therapy to death, emigration, or 31/12/2014. We used Cox regression to compute hazard ratios (HR) and associated 95% confidence intervals (95%CI) for PD-L1, EGFR and KRAS. Results: Among 368 patients, 204 (55%) were men, 250 (68%) were aged >60 years at diagnosis, and 95% were ever-smokers. 233 (63%) had adenocarcinoma, 90 (24%) had PD-L1 positive tumors, 28 (8%) had EGFR mutations, and 113 (31%) had KRAS mutations. In the PD-L1 positive tumors, 7% had EGFR and 37% KRAS mutations, respectively. In the PD-L1 negative tumors, 9% had EGFR and 32% KRAS mutations, respectively. Patients with KRAS mutations had shorter survival compared with wild-type patients. Survival was longer for patients with EGFR mutations compared with wildtype patients. PD-L1 expression did not correlate with survival (Table). Conclusions: Our findings suggest that EGFR and KRAS mutations, but not PD-L1 expression, correlate with survival in 2L NSCLC patients. [Table: see text]